An index.html is created for each directory; a directory is created for each category. So, you need to edit category.html.

Did you set the option in links.def to build shtml extensions, instead of .html? The templates are in the cgi-bin, and are used to build static pages in the non-cgi part of your site (also defined in links.def). (Well, some of the templates are used on-the-fly in the cgi-bin, eg: search, add, etc.)

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